Yes, folks: it’s another post about the gut. But today’s advice is geared toward all the Primal babies out there in preconception, in utero, and in diapers. Because for the first few years, they’re pretty helpless and ignorant in matters of the gut. They need your help to establish and maintain a healthy intestinal environment. They need your expertise and guidance and occasional intervention. And sometimes, as you’ll see, they need you to give them the freedom to do some often unpleasant-looking activities that pay dividends to longterm gut health.

Since most of the immune system resides in the gut, and the development of a kid’s gut microbiome is in many ways the development of his immune system, this turns out to be a helpful guide for parents interested in optimizing their child’s immune system.

Prenatal Considerations

Avoid obesity. Maternal obesity during the prenatal period creates an inflammatory placental environment that can predispose the offspring to gut issues after birth[7], including leaky gut[8] and intestinal inflammation. So don’t become obese. And if you are, it’d be ideal to become less so before getting pregnant. This is best done before you get pregnant, as dieting during a pregnancy can be hard on everyone involved and not generally recommended.

Avoid gluten. Studies in diabetic rodents show that a maternal gluten-free diet can improve the gut barrier function[9] and reduce the incidence of diabetes in the offspring, even in non-celiacs.

Take probiotics and eat fermented food. Although researchers used to think that infant guts were completely sterile before birth and only became seeded during their journey through the birth canal, new research is upturning that old assumption[10] and leading scientists now say that the “tenet that healthy fetuses are sterile is insane.” Bacteria is found in amniotic fluid, umbilical cord blood, and the placenta. Colonization of a fetus’ gut begins in the womb. Maternal probiotic usage directly affects the gut microbes of the fetus[11].

Do the “do’s” and don’t do the “don’t”s listed in yesterday’s post on leaky gut[8]. The nutrients your body uses to support the gut barrier are likely the same ones your body uses to support your growing child’s gut barrier. The environmental triggers and stressors that support and impair gut health in your body are likely to have the same effect on the body growing in your womb.

Birth Considerations

If possible, have a vaginal birth. Microbial colonization may start in utero, but the most important exposure to bacteria occurs as the baby travels down the birth canal, through the vagina, and into the world. This only happens in natural vaginal birth.

Home birth might be optimal (but it’s not necessary). One study[12] out of Holland found that kids who were born at home and exclusively breastfed had the most “beneficial” gut microbiome. If you’re comfortable with home birth and are due to have a low risk pregnancy, give it some consideration.

Avoid unnecessary c-sections. Do not avoid c-sections if they are medically necessary. But if you’re faced with the option of a c-section or a vaginal birth, consider that babies born to c-sections are more likely to have decreased microbial diversity[13], impaired immune responses to stimuli, and lower colonization by beneficial bacteria. Boys born via c-section are more likely to have Crohn’s disease[14] and babies of both sexes born via c-section are more likely to develop celiac[15].

In the event of a c-section, give your baby probiotics. Studies[16] show that breastfeeding after a c-section isn’t quite enough to make up the differences in gut flora, so an infant probiotic[17] with the right strains can really come in handy. I also wonder if a vaginal swab from the mother applied to the baby’s mouth and body directly after a c-section would help properly inoculate the gut. Good luck getting your OB to agree to that one!

Postnatal Considerations

Breastfeed. This is the most important one. Breast milk contains probiotics that colonize your baby’s gut and prebiotics that feed the probiotics in your baby’s gut. Chances are, breast milk probably contains other compounds yet to be discovered that also have a beneficial effect on gut health. Be sure to eat a good diet, because the food and nutrients you eat will make it into your milk.

Look for formula with prebiotics. An important component of human breast milk are the human milk oligosaccharides (HMOs), prebiotics that feed, nurture, and promote the establishment of healthy gut flora in the baby. HMOs aren’t yet commercially available, but some prebiotics have been shown to come fairly close. One recent trial[20] found that an inulin-fos blend (this one[21], to be exact) promoted “a gut microbiota closer to that of breastfeeding.” Is it as good as breast milk? No. Better than nothing, though.

Let them play outdoors. Outdoor play is pro-gut for several reasons. If there’s sun out, your kid will get plenty of vitamin D – an important nutrient for the integrity of the gut lining[22]. If they’re outdoors, they’re probably getting exposure to dirt. Dirt is full of microbes (both “good” and “bad”) and the human gut (having evolved in an unsterile, natural environment, i.e. the outdoors) is primed for constant, low level exposure to these soil-based organisms. Playing outdoors, making mud pies, and sampling the culinary offerings of garden soil all help seed the gut. And finally, kids who are allowed outdoor free play are less stressed, less anxious, and happier than kids who are not. Increased stress levels can wreak havoc on the gut by inducing intestinal permeability (PDF[23]) and affecting the stability of microbial populations[24].

Let them play with other kids – even (or especially) the “dirty ones.” Provided you’ve been following as many of the previously mentioned steps as you can, your kid will have a robust immune system and a healthy microbiome that can handle and even benefit from exposure to other child-borne microbes.

Don’t freak out if they eat their boogers. The idea that eating boogers boosts immunity[25] is intuitive, but unproven. One Canadian researcher actually wants[26] to run a human trial to determine if it’s true or not. I don’t want parents to start home brewing booger smoothies drawn from healthy donor noses. That’s extreme (and disgusting). But if you see your kid pick his or her nose and eat it, don’t worry so much. It could be helping. Besides, they’ll do it anyway when you’re not looking.

Don’t demand antibiotics at the first hint of sickness. I’ve said it before[27] and I’ll say it again: antibiotics have done us a lot of good, but they are extremely powerful tools that deserve respect rather than carelessness. New guidelines for childhood ear infections[28] echo my concerns and actually urge caution when it comes to antibiotic prescriptions, citing research that shows most kids get over ear infections on their own within 2-3 days without antibiotics. And many childhood illnesses (like viral ones) don’t even respond to antibiotics, but parents still demand them anyway. Don’t be one of those parents.

Doing all these thing doesn’t guarantee good gut health for your baby, but based on the current levels of evidence available, it’s probably your best shot.

What did I miss? Got any other tips for parents interested in optimizing their baby’s gut health?